Kossel XL 构建记 (1) Shift of linear carriage design, design goals
今天果断放弃了 Johann 的 塑料滚珠线性滑轨方案 主要原因是因为成本（一个 POM 塑料珠的成本大概是 0.3RMB，三块滑轨大概需要 100 颗）以及噪音（塑料珠彼此碰...
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最近 Coursera 上几个有意思的课程
课程太多，一下听不过来，不过还是想记录一下： 算法分析与设计（I) https://www.coursera.org/course/algo 来自：Stanford Univ 概述 _In this course you will learn several fundamental principles of algorithm design. You’ll learn the divide-and-conquer design paradigm, with applications to fast sorting,...
【人生补全系列】锁裤边儿
作为正沿着 geek 的道路走向不归路的我，当然少不了偶尔要挑战一下自己，至于为什么要这样做，借用 TBBT 的一句话说：“BC I can!” 所以，作为最新的挑战...
Some Piano Video Tutorials
I started learning how to play piano a few months ago. Here’s some great video tutorials I’ve found: Canon in D major (Pachelbel): [YouTube](http://www.youtube.com/watch?v=xDObxlDeeRk Howl’s moving Castle Merry-go-round of life (by Joe Hisaishi): [YouTube](http://www.youtube.com/watch?v=Zt86xb7s-Io Summer (slow, by Joe Hisaishi): YouTube From YouTube channels: PianoKeyz and Jane. Enjoy ;-) Here’s some beautiful piece performed by other people in YouTube: Bach air on the G string piano solo Orchestral suite no....
生成量子曲线的代码
c[0, 0, p_, q_] := 1; c[m_, k_, p_, q_] := If[ (k == 0 && m > 0) || k > m, 0, c[m - 1, k, p, q] (Quotient[k p, q] - m + 1 + k) c[m - 1, k - 1, p, q]]; A[p_, q_] := x^q + Sum[ Inverse[Table[Table[c[m, k, p, q], {k, 1, q}], {m, 1, q}]][[q]][[m]] h^(q - m) y^(m - q )...
使用 wget 下载一个目录下的所有文件
今天想下载 MIT 的李代数课程笔记，参见网页：http://math.mit.edu/classes/18.745/Notes/. 突然间忘了 [cciN_bash]wget[/cciN_bash] 的用...